The invention relates to fiber reinforced composite structures with improved directional shear strength properties and to a method for manufacturing such composite structures.
Fiber composites do not display optimum shear strength properties in many applications, particularly where high temperature and high shear loading are combined, e.g., aerospace and turbine or other combustion engine usages. Rather, present composites exhibit difficulty in withstanding the demanding thermostructural requirements placed upon them in such usages.
Several alternative material methods of construction fabrication approaches, including knit 2D/3D constructions or redesigning the end use application have been utilized. However, each of these have inherent deficiencies in their constructions--relative to the inherent requirements of such structures--in terms of providing: resistance to in-process delamination, an optimum balance of material properties needed for in-use application, a mechanism for venting (outgassing) of volatiles generated between plies during the densification process, and ease of use of normal design configurations.
It is therefore a principal object of this invention to provide a fabric composite which exhibits enhanced tailored anisotropic shear strength properties consistent with meeting the other simultaneous requirements of such structures.
It is a further object of this invention to provide such composite which is suitable for applications such as for rocket and aircraft components, e.g., nose cones, parts for turbine and other combustion engines, and other thermostructural applications.
A further object of this invention is to provide constructions capable of sustaining fabrication (lay-up and/or molding) processing, resin impregnation and subsequent carbonization and graphitization processing without inducing wrinkles, fiber distortion, and/or delamination.
A further object of this invention is to provide a method for constructing such composite structures.
A further object of this invention is to provide an effective use of optimum warp to fill ratios of fabric.